Dynamic weight and sensitive factor-based geological suitability evaluation of underground space development in Yangtze delta’s Hangjiahu plain

This study proposes a comprehensive evaluation model integrating dynamic weighting (DW) and sensitive factor evaluation (SFE) to assess underground space development in the Hangjiahu Plain. The model constructs a refined index system by analyzing the engineering geological conditions across shallow (0-10 m), middle (10-30 m), and deep (30-60 m) layers, and introduces variable weight theory to dynamically adjust the weight, thus addressing key limitations of the traditional fixed-weight model. The results showed that the area of the forbidden development zone of Grade IV in the shallow layer increased substantially and was mainly affected by the thickness of the soft soil. The area of Grades I and II in the middle layer decreased from 97.42% to 51.49%, while the area of Grade IV in the deep layer increased to 81.96%. All sensitive factors are located in the Grade IV area, which is further expanded after weight adjustment, indicating that the model can effectively identify high-risk areas. The model was further examined through a rail transit planning and route selection case in the study area, providing contextual support for its applicability at the regional planning stage. This study provides a theoretical basis for sustainable urban underground space utilization and a reference for similar geological regions.